I 



FiLiCEs. (true ferns.) 441 



4. PELLiEA, Link. Cliff-Brake. 



Allied to Cheilanthes, from which it differs chiefly iu the continaous invo- 

 lucre and smooth fronds (without tomentum or scales). 



* Fronds herbaceous or sub-coriaceous ; veins clearly visible; involucre broad and 



usual! ij covering the sporangia till they are full y ri^je. 



1. P. Breweri, Eaton. Rootstock short, densely covered with narrow ful- 

 vous chaff: fronds membranaceous, 2 to 6 inches loujr, simply pinnate with 

 mostly unequally 2-lobed pinnce. — Proc. Am. Acad. vi. 555. From Colorado to 

 Utah and California. In clefts of rocks. 



2. P. gracilis, Hook. Rootstock very slender, a-eepinrj, nearly naked: 

 fronds very delicate, 2 to 4 inches long, oblong-ovate, pinnate with a few once 

 or twice pinnaiifd pinnce ; segments oblong or obovate ; involucres broad and 

 delicate. — From Colorado northward, eastward through Britisli America, and 

 southward again into Iowa, Pennsylvania, etc. Crevices of damp and shaded 

 linxestone rocks. 



* * Fronds siibcoriacecms or coriaceous: veins rather obscure; involucre con- 



spicuous. 

 •»- Pinnules obtuse, at least not mucronate : fronds 1 to 2-pinnate. 



3. P. atropurpurea, Fe'e. Frond 6 to 12 inches long, evergreen, nearly 

 smootli, ovate-lanceolate, usually bipinnate below, simpler upwards; pinnules 

 oval to linear-oblong, ^ to 2 inches long. — From Arizona and Alabama 

 northward to British America and Canada. Crevices of shaded limestone 



rocks. 



+- H- Pinnules decidedly acute or mucroncUe. 



4. P. Wrightiana, Hook. Fronds 4 to 8 inches long, lanceolate to tri- 

 angular-ovate, bipinnate; pinnae longer than broad, having 3 to 13 oval or 

 oblung-oval pinnules, fertile ones with the margins rolled in to the niidvein. — 

 From Colorado and Arizona to W. Texas. Mostly in exposed rocky places, 

 especially in cailons. 



5. P. densa, Hook. Fronds 1^ to 2 inches long, ovate, closely tripinnate; 

 ultimate segments linear, 3 to 6 lines long, sessile, sterile ones serrated. — In 

 Caliioruia and Oregon ; also at Jackson's Lake, Wyoming ( Coulter). Clefts 

 of rocks. 



5. CRYPTOGRAMME, R. Brown. Rock-Brake. 



Fronds rather small, and smooth, 2 to 4-pinnate, the fertile ones taller than 

 the sterile: stalks stramineous and tufted on a short rootstock. 



1. C. acrostichoides, R. Br. Fronds 2 to 4 inches long, chartaceons, 

 ovate, closely 2 to 4-pinnate ; pinnules ovate or obovate, adnate-decurrent, 

 those of the fertile fronds narrower and longer, the involucres very broad : sori 

 extending far down the veinlets. — AUosorus acrostichoides, Spreng. From 

 California, Colorado, and Lake Superior, northward to Arctic America. In 

 dense patches among rocks. 



